orrrrr it's a known software glitch that others have encountered, including myself. has it ever "freaked out" while you were in the messages app and began scrolling down or highlighting certain messages in green on its own also? that's the glitch...order a replacement.

This is also happening to me, with a brand new (replacement) Incredible. I tried weeding out conflicting apps, to no avail. The fact that it is optical doesn't help. I can move my finger scant microns above the surface of the trackball and the screen changes. I'd love to disable it in all cases except clockwork and camera.